Chest drainage tubes are used following thoracic surgery, chest trauma or to treat certain medical conditions. The purpose of a chest tube is to remove buildup of excessive body fluids, contaminants or air from the thoracic cavity. The presence of an opening into the chest or thorax, created with or without a cannula will cause pneumothorax (collapsed lung). Negative pressure in the chest cavity is created by the chest muscles and diaphragm in order to cause lung expansion and resulting inspiration of a breath. Therefore, a hole in the chest will equalize pressure and prevent critical lung function, i.e. lung insufflation. Any cannula placed into a patient's chest cavity for drainage must be sealed to prevent pneumothorax from occurring.
Current chest drainage cannulae, also called chest tubes, drainage catheters or drainage cannulae, are flexible polymer tubes, placed into the chest cavity and extending outside the patient.
Chest drainage tubes are placed using a surgically invasive procedure. Generally, if a surgical incision into the chest has not been made, the chest tube is usually placed with the aid of an internal trocar that stiffens the chest tube and allows for easier chest wall penetration during placement. The procedure begins with a skin incision large enough to accommodate the diameter of the selected chest tube. Chest tubes are typically 8 mm to 10 mm diameter. The internal trocar, having a sharp point, is placed inside the chest tube. The pointed end of the trocar chest tube combination is pressed through the skin incision and plunged into the thoracic cavity through the muscle, fascia and fat layers of the patient, through the rib space and into the pleural cavity. The trocar is removed and the chest tube is clamped to prevent pneumothorax.
When drainage is required, the clamp is opened and fluid, air and contaminants are removed from the thoracic cavity. The fluid, air and contaminants typically are removed, forcefully, by use of external vacuum or pumping systems. The clamp is closed once drainage is completed to avoid reflux of fluid and air back into the chest cavity and possible generation of pneumothorax or influx of contaminants (i.e. infectious agents).
Placement of current chest drainage tubes is an invasive surgical procedure. With any invasive surgical procedure, there exists a risk of iatrogenic trauma to the patient. Significant training is required to safely perform these procedures and this training may not have been completed by emergency personnel who are the first line of treatment for many patients experiencing trauma.
Improved valving mechanisms would increase functionality of chest drainage tubes and overcome issues that occur with clamp application and removal. There are also fewer steps required of the medical practitioner in chest drainage when a tube with an internal valving mechanism is employed. There may also be a problem with a chest tube being pushed too far into the patient, resulting in kinking, compromised drainage and potential iatrogenic damage to internal organs.